JS: prevent a null pointer exception from the save-as menu
JS: prevent a null pointer exception from the save-as menu

When a config file has not yet been loaded, don't bother trying to set a default
directory for the save dialog.

Signed-off-by: Harvey Harrison <eadbd6b462bf3c97df0300a934c12bc2e5d1fe51@ausenco.com>

jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim